added early epoch stopping hook

src/pytorch-lightning/models/trainer.py

@@ -266,6 +266,10 @@ class Trainer(TrainerIO):
                 if met_batch_limit:
                     break
 
+                # give model a chance to end epoch early
+                if self.model.should_stop_epoch():
+                    break
+
                 # ---------------
                 # RUN TRAIN STEP
                 # ---------------

src/pytorch-lightning/root_module/hooks.py

@@ -18,3 +18,6 @@ class ModelHooks(torch.nn.Module):
 
     def on_post_performance_check(self):
         pass
+
+    def should_stop_epoch(self):
+        return False